Ink jet printing systems typically consist of an ink delivery system connected to a print head. The print head has electronics that control the flow of ink from the ink delivery system through the print head to the print substrate, such as paper. The ink delivery system typically connects to the print head through a conduit using a quick connect/disconnect device. A vacuum pump may provide the optimized operating print head pressure.
Connection and disconnection of the conduit may cause negative pressure spikes that draw air bubbles into the print head apertures. During printing, physical movement of the print head and complex fluid interactions can also result in ink pressure spikes. Air bubbles cause defects in the printed image, because instead of jetting ink, they jet air, so no ink lands on the substrate. In addition, the burst of air can cause spattering and other defects.
Many solutions to managing air in filling and using printing systems involve redesigning various aspects of the printing system.